twenty one steel construction: bolted & welded connections ARCHITECTURAL STRUCTURES: FORM, BEHAVIOR, AND DESIGN DR. ANNE NICHOLS SPRING 2015 lecture

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1 ARCHITECTURAL STRUCTURES: FORM, BEHAVIOR, AND DESIGN DR. ANNE NICHOLS SPRING 2015 lecture twenty one steel construction: nrmc.org bolted & welded connections Steel Bolts & Welding 1

2 Connections needed to: support beams by columns connect truss members splice beams or columns transfer load subjected to tension or compression shear bending Steel Bolts & Welding 2

3 Bolts bolted steel connections Steel Bolts & Welding 3 (AISC - Steel Structures of the Everyday)

4 Welds welded steel connections Steel Bolts & Welding 4

5 Bolts types materials high strength A307, A325, A490 location of threads included - N excluded - X friction or bearing (SC) always tightened Steel Bolts & Welding 5

6 Bolted Connection Design considerations bearing stress yielding shear stress single & double member rupture Steel Bolts & Welding 6

7 Bolts rarely fail in bearing holes considered 1/8 larger shear & tension single shear or tension double shear R R = F n n a n n R A b n R = F 2A b Ω R u φ v φ v R = 0.75 n Steel Bolts & Welding 7

8 Bolts Steel Bolts & Welding 8

9 Bolts bearing deformation is concern deformation isn t concern long slotted holes R a n = 0.75 φ R =1. 2L tf 2. 4dtF n L c clear length to edge or next hole (ex. 1¼, 3 ) c c u u R φr u n R =1. 5L tf 3. 0dtF R =1. 0L tf 2. 0dtF n R n Ω c u u u u Steel Bolts & Welding 9

10 Bolts Steel Bolts & Welding 10 Lecture 121

11 Welded Connection Design considerations shear stress yielding rupture Steel Bolts & Welding 11

12 Welded Connection Design weld terms butt weld fillet weld plug weld throat field welding shop welding (AISC - Steel Structures of the Everyday) Steel Bolts & Welding 12

13 Welded Connection Design weld process melting of material melted filler - electrode shielding gas / flux potential defects weld materials E60XX E70XX F EXX = 70 ksi Steel Bolts & Welding 13

14 Welded Connection Design shear failure assumed throat T = x weld size area A = T x length of weld weld metal generally stronger than base metal (ex. F y = 50 ksi) Steel Bolts & Welding 14

15 Welded Connection Design 16 minimum table maximum material thickness ( to ¼ ) 1/16 less min. length x size min. 1 ½ Steel Bolts & Welding 15

16 Welded Connection Design shear R a R n Ω R φ R u n φ = 0.75 R = 0. 6F Tl = n EXX Sl area table for φs Steel Bolts & Welding 16

17 Framed Beam Connections angles bolted welded Steel Bolts & Welding 17

18 Framed Beam Connections terms coping (AISC - Steel Structures of the Everyday) Steel Bolts & Welding 18

19 Framed Beam Connections tables for standard bolt sizes & spacings # bolts bolt diameter, angle leg thickness bearing on beam web Steel Bolts & Welding 19

20 Framed Beam Connections welded example (shear) (AISC - Steel Structures of the Everyday) Steel Bolts & Welding 20

21 Framed Beam Connections welded moment example (AISC - Steel Structures of the Everyday) Steel Bolts & Welding 21

22 Framed Beam Connections welded/bolted moment example (AISC - Steel Structures of the Everyday) Steel Bolts & Welding 22

23 Framed Beam Connections welded/bolted moment example (AISC - Steel Structures of the Everyday) Steel Bolts & Welding 23

24 Beam Connections LRFD provisions shear yielding shear rupture block shear rupture tension yielding tension rupture local web buckling lateral torsional buckling Steel Bolts & Welding 24

25 Beam Connections φ = 0.75 Rn = 0.6 Fu Anv + U bs Fu Ant 0.6 Fy Agv + U bs Fu Ant where Ubs is 1 for uniform tensile stress block shear rupture Steel Bolts & Welding 25 tension rupture

26 Other Connections seated beam continuous beam to column beam to beam Steel Bolts & Welding 26

27 Other Connections splices The Royal Ontario Museum Toronto. Canada Daniel Libeskind (AISC - Steel Structures of the Everyday) Steel Bolts & Welding 27

28 Other Connections rigid frame knees gussets & joints (AISC - Steel Structures of the Everyday) Steel Bolts & Welding 28

29 Other Connections base plates anchor bolts bearing on steel bending of plate Steel Bolts & Welding 29